Sensor, Coolant Temperature: Operation

At key-on, the Powertrain Control Module (PCM) sends out a regulated 5 volt signal to the Engine Coolant Temperature (ECT) sensor. The PCM then monitors the signal as it passes through the ECT sensor to the sensor ground (sensor return).

When the engine is cold, the PCM will operate in Open Loop cycle. It will demand slightly higher idle speeds. This is done until normal operating temperatures are reached.

The PCM uses inputs from the ECT sensor for the following calculations:

• For engine coolant temperature gauge operation through CAN BUS communications
• Injector pulse-width
• ASD relay shut-down times
• Pulse-width prime-shot during cranking
• O2 sensor closed loop times
• EGR solenoid on/off times (if equipped)
• Radiator fan relay on/off times (if equipped)
• Target idle speed